Plans for a controversial multibillion-dollar U.S. nuclear research reactor are coming together at lightning speed—much too fast, say some nuclear policy experts. With a push from Congress, the Department of Energy (DOE) has begun designing the Versatile Fast Neutron Source, which would be the first DOE-built reactor since the 1970s. It would generate high-energy neutrons for testing materials and fuels for so-called fast reactors. But U.S. utilities have no plans to deploy such reactors, which some nuclear proliferation analysts say pose a risk because they use plutonium, the stuff of atomic bombs.

Researchers are divided on whether the reactor, which would likely be built at Idaho National Laboratory (INL) near Idaho Falls, is badly needed or a boondoggle. “Definitely, there is a lack of capability in the U.S. and a shortage of such facilities worldwide,” says Massimiliano Fratoni, a nuclear engineer at the University of California, Berkeley. But Frank von Hippel, a nuclear physicist at Princeton University, says, “It’s a pork-barrel project.”

The reactor does enjoy extraordinary congressional support. In March, Congress gave the project $35 million for this year, although DOE only requested $10 million. The House of Representatives and the Senate have passed separate bills that call for completing the facility by 2025, with the House bill authorizing DOE to spend $2 billion. Von Hippel speculates that the cost could end up reaching $10 billion.